Crossword Genius

Pseudonym one's forgotten, unfortunately (4)

Ross

I believe the answer is:

alas

'unfortunately' is the definition.
(I've seen this before)

'pseudonym one's forgotten' is the wordplay.
'pseudonym' becomes 'alias' (I've seen this before).
'one' becomes 'i' (Roman numeral).
'forgotten' is a deletion indicator.
'alias' with 'i' removed is 'ALAS'.

(Other definitions for alas that I've seen before include "Unhappily" , "Proper, respectable" , "More's the pity" , "Oh dear!" , "Too bad, so sad" .)

I've seen this clue in The Telegraph.
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